The invention relates to an apparatus for imparting a simultaneous rotational movement to an object moving along a rectilinear trajectory, with a straight guide. This apparatus comprises a partially spiral guide trajectory and a slide that is positioned around the guide, that is movable to and from relative thereto. The slide is provided with a follower which engages the guide trajectory for rotating the slide about the guide in the region of the spiral guide trajectory.
A known apparatus of the type referred to above, is often used in machines that perform a special operation. An example of such a machine is an apparatus for removing the craw of slaughtered poultry. In such an apparatus a mandril with projections is moved through the abdominal cavity and the neck of the slaughtered poultry to remove the craw. During at least part of its motion the mandril rotates about its own axis to optimize its function. Therefore, the mandril simultaneously carries out a rectilinear movement along its central axis as well as a rotational movement about the central axis.
For achieving this rotational movement of the mandril, which is connected to the slide, the guide is provided with at least a partially spiral groove which engages a pin attached to the slide. If the slide is moved along the guide the pin will, first run through a straight groove section such that the slide will not rotate. After reaching the spiral groove section however, the slide will, apart from its rectilinear movement, also carry out a rotational movement.
A disadvantage of the known apparatus is that the cooperation between the pin and the groove results in a high friction and, therefore, leads to excessive wear of the respective parts. Moreover, the high friction requires a high driving power of the apparatus and, thus, heavy and expensive motors.